Popcorn or popping corn is a type of maize which puffs up when it is heated in oil or by dry heat. Special varieties of corn are grown to give improved popping yield. Some wild types will pop, but the cultivated strain is Zea mays L. subsp. mays (Everta Group), which is a special kind of flint corn. Popcorn was first developed by precolumbian Native Americans thousands of years ago. The oldest ears of popcorn ever found were discovered in the Bat Cave of west central New Mexico in 1948 and 1950. Ranging from smaller than a penny to about 2 inches, the oldest Bat Cave ears are about 5,600 years old. Popcorn was introduced to the west for the first time in 1492, when Christopher Columbus noted that the natives of the West indies made popcorn corsages and popcorn headdresses which they sold to Columbus' sailors. French explorers around the year 1612 in the Great Lakes region documented use of popcorn by the Iroquois who popped corn in pottery using hot sand. They also noted that during an Iroquois dinner, popcorn soup and popcorn beer were consumed. Since then, popcorn has become a popular snack food all over the world. Apparently, early north American colonists loved popcorn so much, that they actually served it for breakfast with sugar and cream. This thus represents the first puffed breakfast cereal. Popcorn is a whole grain food.

In Europe and the United States, popcorn is particularly common in movie theaters. It is often served with (often imitation such as margarine) butter and salt. It is also sometimes flavored with sugar (especially in Asia), nutritional yeast or spices. In the United States it is sometimes served with sugar and vinegar.

Popcorn balls (popped kernels stuck together with a sugary "glue") were hugely popular around the turn of the 20th century, but their popularity has since waned. They are still served in some places as a traditional Halloween treat. Cracker Jack is a popular, commercially produced candy that consists of peanuts mixed in with caramel-covered popcorn. Kettle corn is a variation of normal corn, cooked with white sugar in a large copper kettle. Once reserved for specialty shops and county fairs, kettle corn has recently become a popular variety in the microwave popcorn market.

Six popular brands of popcorn in the United States are Orville Redenbacher, Act II, Jiffy Pop (all three of which are brands of the ConAgra Foods conglomerate), Pop Secret, Jolly Time and Black Jewell, a premium specialty brand.